John Gruber has found out that cross-compilers are no longer allowed in iPhone OS 4.0. "My reading of this new language is that cross-compilers, such as the Flash-to-iPhone compiler in Adobe's upcoming Flash Professional CS5 release, are prohibited. This also bans apps compiled using MonoTouch - a tool that compiles C# and .NET apps to the iPhone. It's unclear what this means for tools like Titanium and PhoneGap, which let developers write JavaScript code that runs in WebKit inside a native iPhone app wrapper. They might be OK."

As a game developer, this sucks. I hope Adobe and all game development studios push apple really hard for this. Imagine what would happen if Microsoft, Sony or Nintendo were to forbid cross platform code! It would be kind of like "Only exclusives allowed, sorry!"